Troubleshooting a TrailStar Trailer that Running Lights Only Work on the Left Side

Question:

I have a newish, april 2013, trail star trailer. The brake lights bulbs have 2 filaments in them. Both come on when the brake is on. My left side single filament works for just driving lights but the other filament doesnt come on when brakes are on.only on the left side, right works great I switched out bulbs and still the same. Switched out fuses on the truck we use, f150, and still out. Any other suggestions?

asked by: Sandy

Expert Reply:

It sounds like the problem is in the way your left side tail light is wired, does your left turn signal work? I would go over the wiring and make sure that the brake/turn signal wire is attached to the correct circuit of the light and the tail light function is connected to the other. It almost seems like you might have both trailer light circuits run to one circuit of the tail light.

I attached an FAQ article on trailer wiring for you to check out also that might be helpful.

expert reply by: Jameson C